I've been working for a few weeks on many different track designs and redesigns of existing tracks. And I thought 'Hey, why not posting the tracks I've drawn so far?', so here they are.
Would like to hear your opinion about them. If you want, you can redesign them ;D

1) the opening sequence is terrifying. Initial starts may have to take place between T13 and T14.

The gravel trap at T14 is useless where it sits.

If a car were to go off at T16, extricating it could require an extended FCY/Safety Car.

Normally I wouldn't do this, but since the rest of the kerbing is so excellently placed, there should be kerbing on the outside of T17, inside of T18, outside of T23-24, and extend the kerbing inside of T24 to pit-in.

2) The bottom end is a bit fiddly after the middle sector and the right angle corner leading to not the beginning of Spa is too tight for practicality.

3) overly long corners are just annoying in modern cars and the entrance to the hairpin at the bottom is awkward at best.

4) First and last chicanes are a bit tight as are the second and third hairpins.

1.
My least favourite, I'm guessing it's the first design you sketched here? (The other ones seem a bit neater with a more developed style). As AOB mentioned there are some runoff issues at T1, T7, T8, T14, and T16 (where's turn 15? ). I feel the circuit lacks an overall flow, the others are much better.

2.
If the top hairpin is styled like the Magny Cours corner, it works well. Sometimes are can be too many configuration options, how could any organisers decide which to use?! Maybe remove a few options in the infield and this could be a nice design.

3.
I really like this one! I like the first chicane and the flyover section at the bottom, though the barrier detail in this area could be tricky to work out. I don't think this circuit needs that little loop at the end of the lap, just a simple medium-speed right hander would finish the lap nicely.

4.
This one reminds me a lot of the french circuit mentioned earlier, and it looks great. I don't mind the hairpins, perhaps the first one (T5?) could be opened a little. The only things that I think need looking at here are the pit entry and exit, and the lack of runoff area at T1. If you have any questions about the pitlane, let me know.

5.
I think the section from the ascari-like chicane to lower pitlane pit-out are great, but the other half of the circuit might need some adjusting, especially the upper pitlane.

6.
Probably my favourite, though I might have made some controversial adjustments.... I think the circuit works better as a compact motorsport complex, I'm not sure the extra loop added anything. What do you think?

I can see there is a clear progression being made through the designs as you have presented them. The placement of the kerbs and the run-offs was haphazard, but now looks like you've thought about the direction of travel a lot more.
The fact that you have tidied up the the curves and actual corners a helps with that, and the more you designs you do, you'll come to think of if I make the tune this much, where does the run off go, ...is that too close to another piece of track etc. I feel you have run into that in the middle grouping of the circuits, but have started to understand that with the latests ones.

Looking at number 3, SKG has suggested removing the top loop, which I'd agree with, but what I'd also suggest is that the bottom right hairpin. I'd have brought that off the long curve earlier, right down the edge of the paper to be honest, have the hairpin but I'd have the circuit pass under the curve. I don't like bridges over curves due to the width of the track allowing for run off on the curve plus the angle of the bridge meaning in a real world sense a very long unsupported section.
In this case it would be a straight line tunnel opening out into an uphill right hander leading to the infield hairpin.

One other thing on this design, the I'd swap the chicane at the left hand end of the bottom straight with the T1 chicane as drawn. The more open second phase would allow for better starts, with less chance of first lap accidents.

I do like the concept though.

The final one of the group, I think less is more.where i disagree with SKG, is that I'd leave in the right hand loop as it's got a long straight with space for a pit lane especially if you get rid of the "Mallory park" hairpin. leaving the big swinging esses into the Oulton Park loop,